1. Field of Invention
This invention relates to remote monitoring and more particularly to remote monitoring in an electronic location monitoring system.
2. Description of Related Art
As an alternative to incarcerating offenders for minor infractions, more and more judicial and law enforcement agencies prefer to place such offenders under house arrest and monitor their movement using electronic location monitoring equipment. As a result, there is less space taken in already overcrowded detention facilities such as prisons, thus eliminating the cost of incarceration, while at the same time allowing offenders to avoid prison and provide them with the opportunity to attend school or earn a wage and participate in counseling or rehabilitation programs.
Electronic location monitoring equipment usually involves the use of an identification tag securely attached to the individual's body, which periodically transmits a unique code to an RF receiver device placed in the incarcerated individual's place of confinement (usually his or her house). The receiver listens for transmissions from the identification tag, and if a transmission is not received within a predetermined amount of time, an event is logged by the receiver indicating that the identification tag, and hence the individual wearing it, is no longer in the vicinity of the receiver. In turn, the receiver transmits a status message to a monitoring station over a communication channel such as the PSTN (Public Switched Telephone Network) indicating the presence or absence of the individual at the monitored site.
The electronic location monitoring approach described above works well to ensure that the individual remains in the monitored area according to the conditions of his/her parole. However, once the individual is away from the monitored site and out of range of the receiver, the individual cannot be reached. Law enforcement agencies usually want to ensure that the individual is at particular locations (not just one monitored site) at particular times. For example the individual may be required to be at work during certain hours, at a counseling workshop during other hours, and at home at all other times. In some cases, it is also necessary to ensure that the individual stays away from certain locations (for e.g., schools, parks, home of an ex-spouse, etc.).
To overcome this problem, systems are known in which an incarcerated individual wears a transmitter and carries a receiver operable to receive signals from the transmitter. The receiver may perform calculations based on position signals it may receive to determine whether the individual is in an allowable location and may permit the individual to venture outside of a single area. One problem with this type of system however is that the individual must carry the receiver with him/her at all times, which can be somewhat inconvenient. For example when the receiver is being charged, the individual must stay relatively near the charger. Consequently, this type of system can be restrictive.